Investigations in this laboratory over the past several years have been instrumental in establishing that collagen molecules collectively represent a family of chemically-distinct, albeit functionally-related proteins. The biological significance of some of the different types of collagen is underscored by their general distribution pattern among and within tissues as well as the tendency of individual molecular species to form unique and readily distinguishable functional aggregates in the extercellular spaces of various connective tissues. The present continuation application has been formulated to address key remaining issues relevant to the molecular diversity of the collagen family. The application focuses on two of the quantitatively "minor" collagens, i. e., type V and XI. The overall objectives of the program are to extend and essentially complete the biochemical characaterization of these collagens and their constituent chains and elucidate the chemical and topological relationships of these collagens to the more prevalent collagens in selected tissues. Specifically, the tissue forms of these collagens will be prepared by extration from appropriate sources and the constituent chains resolved by chromatographic techniques. Individual chains recovered in this fashion will be characterized with respect to number and nature of the CNBr cleavage products with emphasis on the alpha 3(V) chain and the 1 alpha chain of type XI collagen. Using these data and information available from previous studies, the cross-linking patterns of type V and XI collagen will be evaluated as a function of radioactivity associated with discrete peptide fragments following borotritide reduction of cross-links in selected tissues. Further studies on the radioactive peptides will be conducted to discern the nature of the chains joined by the cross-links. In addition, a systematic study of the ability of type V and XI collagens to form fibrous and/or alternate aggregate forms when precipitated alone and in the presence of other collagen molecular species will be undertaken. And finally, information garnered in the aforementioned studies will be complemented by studies leading to the fabrication of monoclonal antibodies to the collagaens and use of the antibodies for localization at the light and electron microscope levels. It is anticipated that the results of the proposed studies will considerably enhance current information with respect to the chemical properties of these minor collagens and facilitate a critical assessment of their discrete biological roles.